Characterising stormwater gross pollutants captured in catch basin inserts.

Area of Science:

• Environmental Engineering
• Water Resource Management
• Urban Hydrology

Background:

• Gross pollutants (GPs) in stormwater drainage systems pose significant challenges to best management practices (BMPs).
• Capturing GPs at the source is crucial to prevent drainage network clogging, maintain infiltration capacity, and protect aquatic ecosystems.
• Catch basin inserts (CBIs) offer a land-use-efficient solution for in-situ GP removal within existing infrastructure.

Purpose of the Study:

• To evaluate the performance of a novel catch basin insert (CBI) developed by Urban Stormwater Technologies (UST).
• To assess the CBI's capacity for capturing gross pollutants (GPs) down to 150μm particle size over a one-year period.
• To analyze the characteristics and accumulation rates of GPs captured by the CBI.

Main Methods:

• Installation and monthly servicing of UST-developed CBIs at a site in Gosnells, Western Australia.
• Collection and analysis of gross pollutant (GP) mass, moisture content, and particle size distribution data over one year.
• Correlation analysis between GP accumulation, rainfall patterns, and location-specific factors (e.g., proximity to trees).

Main Results:

• The primary component of captured GPs was vegetation (93%), with accumulation strongly correlated with rainfall (r²=0.9), particularly during the wet season.
• The average total GP load was 384 kg/ha/yr (dry mass), with moisture content ranging from 24% to 52.5%.
• The UST CBI demonstrated a higher potential for capturing GPs down to 150μm compared to previously studied devices, with higher loading rate coefficients (K) observed near trees.

Conclusions:

• The novel UST CBI is highly effective in capturing fine gross pollutants (GPs) down to 150μm, including significant amounts of vegetation.
• The device maintains its pollutant-capturing capacity for at least one year, offering a durable stormwater management solution.
• CBIs, particularly the UST design, represent a promising and efficient BMP for mitigating GP impacts in urban stormwater systems.